In the Glickman U.S. Pat. No. 5,061,219, there is disclosed a multi-part construction toy utilizing a novel form of rod and connector system which enables rods to be joined with connectors by a lateral, snap-in motion into sockets provided by the connector elements. In the subsequent Glickman U.S. Pat. Nos. 5,137,486 and 5,199,919, there are disclosed modified forms of connector elements in which two connector parts are joined together in a fixed relation, with one connector part being in a plane oriented at right angles to the plane of the other connector part. The resulting connector enables rods to be assembled in two planes, facilitating the construction of three-dimensional structures. Construction toy sets incorporating these features are sold commercially under the trademark K'NEX by K'nex Industries, Inc., Hatfield, Pa.